package com.tian.auto.test;

/**
 * Description: <<深入理解JVM虚拟机>>演示对象的自我拯救
 *
 * Author:  tianjinyong
 * Date:    2019-11-15 13:44
 */
public class FinalizeEscapeGC {
    public static FinalizeEscapeGC SAVE_HOOK = null;

    public void isAlive() {
        System.out.println("yes ,i am still alive");
    }

    @Override
    protected void finalize() throws Throwable {
        super.finalize();

        System.out.println("finalize method executed");
        SAVE_HOOK = this;
    }

    public static void main(String[] args) throws Throwable {
        SAVE_HOOK = new FinalizeEscapeGC();

        //对象第一次成功拯救自己
        SAVE_HOOK = null;
        System.gc();

        //因为finalize方法优先级很低，所以暂停0.5s等待它
        Thread.sleep(500);

        if (SAVE_HOOK != null) {
            SAVE_HOOK.isAlive();
        } else {
            System.out.println("no, i am dead");
        }

        //下面这段代码和上面完全相同，但是这次自救却失败了
        SAVE_HOOK = null;
        System.gc();

        Thread.sleep(500);

        if (SAVE_HOOK != null) {
            SAVE_HOOK.isAlive();
        } else {
            System.out.println("no, i am dead");
        }
    }
}
